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a unique aspect of the San Francisco Experimental Vessel Traffic System has been its extensive use of real time automatic processing technology. Automatic detection and tracking of vessels in radar coverage areas has successfully been accomplished even in the presence of clutter. Vessel movement information has been extracted, presented to operators on computer-animated displays, and traffic analyzed both automatically and at the request of operators. But these demonstrated capabilities should be employed only as a guide to the design of future systems and not interpreted as a literal prototype configuration. Future system designs should assume traffic will be controlled, rather than advised. Risk analysis based upon port geometry, traffic levels, and minimum turning radius can contribute to assessing deployment priorities. Vessel routing should be constrained to follow narrow tracks rather than broad lanes. A minimum configuration would be based upon a computerized Vessel Movement Reporting (VMR) system. Data entry and retrieval terminals could be available within the maritime community. Information, including guidance, could be selectively distributed to active ships via a novel multiplexed television transmission. All radar configurations would include automatic detection and tracking equipment. Finally, area navigation systems could be integrated with VTS. The opinions expressed in this document are those of the author, presented in the interest of stimulating discussion, and they do not necessarily reflect the views of either the Applied Physics Laboratory or the United States Coast Guard.

The National Maritime Research Center, Kings Point, N.Y., is conducting projects dealing with the “new technology” in the field of navigation. This paper consists of a survey of this area of activity of the Center. The intent is not only to disseminate information to the wide community of navigators but also to structure a mutually beneficial communications link between the NMRC and the Institute of Navigation. The paper will cover the following projects, some innovative, others extensions of previous programs: —RAPS (Radar Automatic Plotting System) —MASS (MarAd Anti-Stranding Sonar) —TRANSIM (Simplified Transit) —MARINE RADAR TRANSPONDER —MARSCAN (Maritime Satellites Communication and Navigation System) —INTEGRATED CONNING SYSTEM

In the course of the past year or so, several papers have been presented here and abroad dealing with the utilization of transponders in ship's navigation. Multiple usage transponder systems are available as aids for both navigation and target recognition by Radar. Extensive research for additional uses of transponders is continuing on a broad scale in the United States and similarly in Great Britain and Holland. A simple system is needed which can operate on present day ships, now-today-with today's personnel. This system must be commercially feasible, in cost and maintenance, and be compatible with presently used instrumentation on board the average ship. The year by year rising losses in life and ships caused by collisions demand it. One proposed system is presented here.

Lacking Compass, sextant, chronometer, radio, radar and inertial navigation aids, “ancient mariners” relied on an observed knowledge of the prevailing winds, tides, and currents; the habits of birds, particularly sea birds; the discontinuities that exist where the sea meets the land; and the stars (1,2). A particularly well developed use of the “natural means” of the Marshallese (3, 4, 5). These Micronesian navigators devised an aid, artistic in execution, but near scientific in design and based primarily on water surface conditions.

the vector analog computer (vac) is a new radio navigational instrument which enables a pilot (1) to fly a rectilinear course either on or off the Victor airways with no appreciable lateral displacement, (2) proceed directly to any given latitude and longitude with exact positional information at all times, (3) navigate directly to any specified holding point and then hold the pattern precisely, (4) make the transition to an ILS approach with extreme versatility, and (5) assist radar traffic controllers by providing more precise information about his aircratt's position in the traffic picture than radar can provide. VAC offers continuous readings of position, bearing, distance, and ground speed with signal reception from only one VORTAC station at a time. After proceeding beyond the range of the VORTAC transmitter it can still navigate for relatively long distances on mechanical memory. It is a superior anti-collision device, is readily adaptable to all aircraft from helicopters to jets, and is capable of directing an automatic pilot independently of the magnetic directional information normally required in beam guidance systems. This paper discusses the limitations of present radio navigation systems, offers a list of criteria for an airborne navigational director with the simplicity and accuracy of visual reference, and then explains the principles of design and operation of the Vector Analog Computer.

The objective of this paper is to identify problem areas in the use of radar and to show the implication of these problems to those involved in ship operations and radar development. The discussion includes the operating procedure for radar, the philosophy of radar use in the merchant service and the modification thereto required by increased speeds and traffic, the relevance of basic operator capabilities, and operator information requirements versus current display capabilities. These problem areas and requirements were identified as one aspect of a study of “Human Factors in Ship Control” conducted for the Maritime Administration (MA-4221). The paper emphasizes the need for research designed to develop a radar system which meets the deck officer's requirements yet which is compatible with his capabilities and the cost constraints of the merchant service.

I have now had the privilege of sailing in the Peninsular and Oriental Company’s liner Canberra for nearly two years, originally as Senior Watchkeeping Officer and for the last year as Navigating Officer, and I am now even mow convinced that the bridge design in Canberra is the only workable one in fast passenger liners on world routes. All officers who have had the privilege of sailing her are agreed that with the increase in the numbers of ships fitted with radar our system and layout are essential for safe navigation where a quick reliable radar plot is required and where all the navigational equipment is at one's finger tips and not buried in obscure corners, as is the practive of most merchant ships.

IN THE YEARS IMMEDIATELY following World War II, marine radar gained a kind of mystical hypnosis over the minds of many mariners. A general feeling existed that a ship with radar was exempt from collision. The records show that this feeling was highly erroneous; so erroneous, in fact, that the expression radar-assisted collision was coined and widely used. As a direct result of a frightening number of post-war collisions involving passenger ships, freighters, naval vessels, and even fishing boats, many individuals and organizations closely studied the available records and offered suggestions and preliminary conclusions. Obviously, the collisions usually were not the fault of radar; most collisions were rooted in misinterpretation of information shown on the radar scope. Consequently, most of the suggestions were based on improving the use of information available from the radar scope. But how was this information used and evaluated? .A look into the past may disclose some interesting information.

this paper discusses applications of inertial navigation to deep submergence operations, both for support ships and for deep submergence vehicles. The basic principles of inertial navigation are reviewed, including the elements required to make up a system and the fundamental error-propagation modes for a pure inertial system. Next are discussed methods of utilizing external information to alter these fundamental error-propagation modes and thus improve system performance. External information sources which could be available for this application include velocity measurement; position from Loran, radar, satellite, etc.; and angular orientation information from star, sun, moon, or planet observations. Both conventional and optimal methods of utilizing these sources are discussed. Because of security reasons, it is not possible to give detailed descriptions and expected performance of specific systems. However, the most generally applicable augmented systems for these applications are briefly described.

The requirement for all-weather, VTOL terminal guidance is established. The recommendation for a first-generation, all-weather terminal landing system for the 1970's is presented. The recommendation includes some aircraft characteristics as well as a combination of airborne and ground-based electronics which includes an autopilot with force stick steering, a self-contained radar guidance system and a microwave type of ILS/DME cooperative guidance system. The recommendation also includes terminal-based, fog dispersal equipment and a definition of visibility minimums. The system gives the pilot essentially “zero-zero” guidance capability. A self-contained, perspective approach radar is described and results given. Developmental obstacles to all-weather landing capability are listed including: long lead times historically related to the multitudinous agencies involved in cooperative electronic systems (not necessarily self-contained), the meaning of redundancy, the role of pilot and co-pilot, etc. Many references are included for more detailed examinations.

Lunar based radar beacons for nearby spacecraft navigation, noting trajectory determination advantages

The solution presented here is based upon Napier's rules for solving right spherical triangles. Accuracy is dependent upon accuracy of construction. The use of a large vernier protractor will result in extreme accuracy. The Radar Plotting Sheet, used with care, will give results which are useable and not far less accurate than the spherical results normally used as compared with the spheroidal shape of the earth.

There are a number of methods for navigating an aircraft over the surface of the earth. In the broad sense these can be divided into two categories: position fising and dead reckoning. Position fixing is accomplished by noting visible landmarks, by radio fixing, such as with loran, TACAN, and Decca, by radar map matching, by earth’s magnetic field intensity and dip measurements, and by astronomical observations. Dead reckoning is the computation of a ship’s position using heading, velocity, and time to determine the change from the last known position. Dead reckoning requires only velocity data and a heading reference as inputs to a navigational computer to determine the positional change of the aircraft over the surface of the earth. The usual directional reference is either true north for conventional latitude-longitude navigation or displaced north for grid navigation or great circle navigation.

A RAPID AND ACCURATE solution to the relative motion triangle is imperative if modern high-speed ships are to operate safely at sea under all conditions. Marine radar of great range, accuracy and flexibility provides early warning of the existence of potential dangers to the new ships, but methods of evaluation of the information provided by radar has not kept place with the advancement of equipment design. The methods commonly taught in the various maritime schools for the solution of the relative motion triangle require transfer of the information provided by the radar to a maneuvering board, conversion of the relative motion line to relative speed and direction, and an ultimate solution for a safe course of action by the maneuvering ship based upon the solution of the speed vector triangle. Since the length of the relative motion line cannot be conveniently measured on the radar scope itself, even when a reflection plotter is provided, this procedure cannot be completed on the reflection plotter. The reflection plotter is now the primary method of plotting the relative motion line and due to this inability to solve the problem on the plotter, or to complete the solution on the maneuvering board in the time available, with the methods currently taught ashore, the ship's officers normally do not carry the solution any further than an extension of the relative motion line to determine the CPA (closest point of approach). Change of course is generally decided by estimate—which is another word for guesswork. The use of a distance vector triangle enables the radar navigator to obtain a rapid and accurate solution on the reflection plotter or on the maneuvering board, with the reflection plotter being the preferred method. All calculations are avoided, as the lengths of the vectors for own ship and target's true course and distance made are based on the time duration of relative movement, and own ship's distance may be precalculated for various plotting intervals. Since the solution is plotted at the location of the relative motion line, the positions of several ships may be plotted simultaneously, and when a new course or speed to avoid one ship is plotted, the effect of this action on the CPA of all other targets may be determined immediately. Errors and loss of time in reading off and transferring data, are avoided and the solution may be arrived almost instantaneously. The Keystone Method of solving the distance triangle has the advantages of simplicity, clarity, accuracy and speed of solution. No navigator plotting by this method has ever been involved in a collision. The inadequacy of the speed vector triangle system of plotting raises a presumption of unseaworthiness of ships relying on this system where collision results from a failure to plot. When all factors are weighed, it seems abundantly clear that a shift to the distance vector triangle plotting method should be made by the maritime industry.

The scan-100 collision Avoidance System (CAS) has been designed to assist in the avoidance of collision at sea by automating the radar plotting functions in a small digital computer linked to the ship's radar. A clear and easily understandable display is provided to present numerical data and computer-generated plots to the ship's officer for evaluation of the radar data and for planning a safe and timely action to avoid collisions. This paper discusses the system design philosophy as implemented and tested in an engineering prototype of the SCAN-100 CAS. This philosophy utilizes an integrated man-machine concept which employs the best capabilities of each. The routine functions of radar tracking and plotting are performed by the system, which then presents the information to the operator in the form of displays combining graphic plots and numerical data. Automatic alarms are provided by the computer, one based on closest-point-of-approach (CPA) and another based on target arrival at a guard-ring distance. A vital requirement for the effective operation of such a radar-based system is the processing of radar data prior to tracking. In particular, the system must distinguish between receiver noise, sea clutter, and valid targets. The SCAN-100 uses a radar preprocessor, especially designed for this purpose, as well as computer processing to achieve the necessary radar signal enhancement. Several aspects of this processing technique are discussed in the paper. The system has recently undergone testing. Results of these tests are also described.

Optimum deployment of deep submersibles to dive sites requires rapid collection of topographic information, intermediate in precision between conventional depth sounding and direct visual observation. The area and depth resolution of conventional depth sounding systems operating from the surface does not provide the detail necessary for submersible operations. High resolution deep-towed side-looking sonar, television, and camera systems require too much pre-dive survey time. The synthetic aperture array technique, originally developed for side-looking airborne radar, provides a potential solution for this problem. Application of this technique to side-looking sonar involves unique problems in the areas of medium stability, vehicle motion compensation, reverberation limitations, and the range-azimuth ambiguities resulting from the relatively low propagation velocity. An investigation of these problems has revealed that the technology required to develop a synthetic aperture side-looking sonar is available. Swath coverage on the order of 10 km with a resolution cell of 10 meters in water depths of 7000 m appears to be feasible, from a surface ship operating at a speed of 10 knots. The synthetic aperture approach appears to offer considerable savings in cost and complexity compared to conventional side-looking sonar arrays of similar performance.

Clear air turbulence detection and warning by airborne devices including radar, IR spectrum, air temperature probes, ozone detection, etc

Air traffic control today depends on radio, radar, and human interpretation thereof. In bad weather, with enlarged air blocks, delays of one to two hours are common, and four-to-eight-hour delays are not uncommon. Were there a means to continuously identify longitudinal position of each aircraft to the order of a few hundred feet on the ground and ½ nautical mile in the air (and even closer on landing and takeoff), and velocity to the order of ½ foot per second, most delays would disappear since aircraft would operate under better than VFR conditions and with improved flight-control inputs. The economic benefits to the airlines in delay time saved would provide a basis for funding the equipment to work the problem in these terms. Tomorrow's commercial inertial navigation can be expected to perform with accuracy measured in hundreds of feet. Using such a system, one can envisage each aircraft knowing its coordinates, velocity, etc., and so informing the air-traffic-control center via data links with the whole operation at computer speeds.

In an attempt to satisfy the need for a tactical aircraft command, control and positioning system, a number of systems have been tried. These candidate systems, including Loran and pulse radar, have provided less than desired performance primarily because of position accuracy. A C-W (continuous wave) radar system patterned after the AN/USQ-28 SHIRAN system shows promise for a more satisfactory solution to the problem.

This paper traces the history of the effort made by those interested in the shipping industry to reduce the loss of life and property caused by marine collisions. It cites the efforts of governments in establishing laws regulating the Rules of the Road, practices of seaman at sea, and in port, and the efforts made by industry and regulatory bodies to make radar an efficient tool for collision avoidance. It describes the latest developments to make use of the digital computer in conjunction with radar and describes the future use of satellites for traffic control and marine communications.

The International Regulations for Prevention of Collisions at Sea (33 U.S.C. 1051), the Inland Rules (33 U.S.C. 154), the Pilot Rules, Great Lakes Rules, Western Rivers Rules and the Admiralty Court decisions which interpret them, form a real and complex system of constraints upon the mariner in the navigable waters of the United States and on the open sea. These Rules are law, both international and U.S., and are used by the Courts in the determination of liability in case of collision. Admiralty Court decisions have modified and clarified the Rules of the Road in many cases. They have also added to the difficulty of the watch officer on the bridge of a ship at sea who must know not only the Rules but the Court interpretations in order to comply with them. The nature of the constraints imposed by these Rules is examined as they apply to the information furnished to the mariner from marine radar and radar based collision avoidance systems. The rules which apply when the vessels are in sight of each other and when they are not are discussed. The information needed to comply with the rules in each case is compared to the information available from radar and collision avoidance systems. The informational short comings of these systems are identified and an ideal collision avoidance system to aid the mariner in maneuvering under the constraint of the Rules of the Road is described.

the effectiveness of the means employed in the search for THRESHER was related strongly to the quality of navigational control. Loran A, Loran C, Decca Navigator, reference buoys, radar, and navigation by echo-sounding and acoustical ranging were all eventually available to the Research Vessel ATLANTIS II during the period April 11 to May 27, 1963. All navigational data were taken as frequently as possible (every one to five minutes), to provide enough samples for statistical treatment. Especially in the case of Loran A early in the search, this procedure provided closer navigational control than ordinarily would be estimated from the known characteristics of the system. Loran C provided but one good line of position. Combinations of lines of position from different systems were used repeatedly, but not generally successfully. Decca Navigator, buoys and radar, and soundings were the most effective of the tools used by ATLANTIS II. With their use, the positions of known fixed objects, such as contact Delta, could be reoccupied reliably. On the other hand, it was not equally possible to relate the positional data from several ships, probably because of differences in navigational technique. Determining the location of deeply towed search instruments in relation to one's ship was another navigation problem, of equal or greater magnitude, which was solved adequately by a method of acoustical positioning.

Operational and technical features of the TM/CPA radar system are described. The equipment has a built-in digital computer and an electronic bearing marker (EBM) controlled by the computer and manually. It provides an easy and accurate means for determining the relative and true speed of course, CPA (Closest point of approach) and time of CPA to any number of targets both in relative and true motion presentation.

THIS PAPER TREATS briefly of the current dissatisfaction in the maritime industry with respect to the efficacy of the conventional means of radar plotting for collision avoidance and suggests possible feasible approaches which may be employed to alleviate the problem, particularly among users without resources for expensive and complex plotting equipments. The suggested means have the objective of working towards reducing the blunders frequently made even by experienced radar observers in the solution of the vector diagram through variations in technique as opposed to the introduction of new principles. A parallel objective is the presentation of the solution in a form which will tend to reduce the confusion frequently associated with relative motion. A desired byproduct is increased solution speed with reduction in the need for continuous attention to the radar plot, particularly for deck watch officers who have multiple duties and responsibilities, with little or no assistance from other qualified personnel. While the paper is directed primarily towards the problems of the merchant marine deck officer, the suggested techniques and their variations applied to radar plotting could prove of benefit to the naval officer. Expanded treatment is given of the alternative solutions presented in the 1968 Corrected Print of H. 0. Pub. No. 257, Radar Plotting Manual. The paper includes a discussion of the relative merits of geographical (navigational) and relative plots used in interpreting the data of relative motion radars. Simple means of rapidly converting a geographical plot to a relative motion plot are investigated. The opinions and assertions contained in this article are not to be construed as being officially endorsed by the Naval Oceanographic Office or the Naval Establishment.

A practical x-band enhances which will respond to marine radars operating in the 9300 to 9500 MHz frequency band without the necessity for radar tuning has been developed by Vega Precision Laboratories and field tested. The reply echo from the all solid state enhancer will be seen as a normal radar echo except that it is fixed high power and coded for identification. If the radar receiver is detuned then the enhancer reply overrides the usual radar clutter such as unwanted echoes from the sea, land or rain. The equipment may be strategically located and used for navigation of rivers and waterways or it may be used to enhance the radar return from small boats for collision avoidance and also search and rescue.

Trilateration computations of radar measurements made between surface ship-based interrogator-responsors and shore-based transponders can be used to obtain better than 2-ft positional accuracy at line-of-sight ranges of the order of 5 mi. Use of nanosecond pulses provides elimination of the usual range errors caused by multipath reflections from sea surface and ship's superstructure. A description of currently available hardware to accomplish these positional accuracies is presented.

A recent shipboard true motion radar display is described. In addition to providing a large, bright picture on a television type screen, the display has electronic storage capability. True motion is provided by a new solid-state computer which is described. Special operator controls permit rapid and accurate determination of target speed and course, thus improving the capabilities of the radar in collision avoidance and piloting.

The effectiveness of a marine radar in the prevention of risk of collision or in guiding a vessel in the proximity of land, depends to a considerable extent on the skill of the navigator. This skill is drawn from his ability to apply the inherent features of the radar to those precautions and techniques which, through his own training and experience he had learned to rely on before the advent of radar. Recently two additional aids have been placed at his disposal; the Reflection Plotter which permits the observer to plot directly over the radar screen, and the Parallel Cursor, whose application has been generally referred to the ingenuity of the navigator. It is the purpose of this paper to explain a system of radar navigation, evolved from basic principles of maneuvering and piloting, but altered to utilize the valuable features of a modern radar. The objective is a simplification of the solution of the associated problems.

The rapid increase in the number of large crude-oil cargo carriers, or supertankers, has created serious problems in the navigation of coastal waters and the pilot's performance of safe docking maneuvers. The economic motivations for the creation of supertankers and the forecasted increase in their sizes and numbers is reviewed. Navigation and maneuvering problems caused by their large masses and sizes, are analyzed. The net result of these problems in reducing the full potential of economic advantage, coupled with increased damage hazard, is outlined. The role of Sonar Doppler systems in reducing these problems is explored. The present state of the art and the techniques used are discussed. Early applications of marine Doppler systems in military vehicles are outlined, and analoiges to airborne Radar Doppler systems are drawn. The limitations of the ocean environment are shown to present certain restraints on expected performance. An analysis of the advantages and disadvantages of pulse and continuous-wave systems is given. A complete description of a channel navigation and docking system now available to the marine industry is presented. The displays available to the watch officer are analyzed and shown. These displays provide him with information sufficient to reduce, significantly, the hazards in navigation and ship handling. Possibilities for expansion into automated ship control for the purpose of reducing human burden and effecting economies are discussed.

In the lower latitudes, celestial provides the navigator with track, groundspeed, and wind information which he normally would not otherwise have. In high latitudes, with the latest type radar and gyros, the navigator as a rule knows the track, groundspeed, and wind with greater accuracy than can be provided by celestial in the span of an hour. Because the ice pack provides correct wind information, dead reckoning (DR) is accurate. Because of the clear, cold, generally stable air, the celestial work is extremely accurate. The navigator, then, is provided with two accurate systems for determining the position of the aircraft. Celestial is a great aid in making minor adjustments to the DR. It is even more welcome as a cross check on the accuracy of the many mathematical computations involved in polar navigation: When the DR and celestial positions disagree by any large amount, the navigator knows immediately that an error has been made in one or the other. When the celestial fix falls right on top of the DR position, the navigator knows more than just the position of the aircraft; he is assured that the heading, drift, track, groundspeed, gyro precession and celestial have all been computed correctly since departing the coast.